It is already a mature technology to apply the earthquake-isolation technology to structural works to reduce the hazard of earthquake. Japan is earlier in research and application of this field. China also carried out application research of this field in recent two decades, and has built a number of earthquake-isolation buildings. The current Chinese seismic design specifications also include the earthquake-isolation design.
At present, the earthquake-isolation supports adopted in the earthquake-isolation structure at home and abroad are rubber supports.
The rubber supports are generally cylindrical, having the vertical bearing capacity of
      N    =          Af      =                                    π            ⁢                                                  ⁢                          D              2                                4                ⁢        f              ,wherein A is the horizontal area of the rubber of the support, f is the compressive strength of the rubber, and D is the diameter of the support. The horizontal stiffness of the cylindrical rubber support is approximately
      K    =                  12        ⁢                                  ⁢        EJ                    h        3              ,wherein E is the elastic modulus of the rubber,
  J  =            π      ⁢                          ⁢              D        4              64  is the moment of inertia of the horizontal section of the rubber, and h is the total thickness of the rubber of the support, thus
  K  =                    3        ⁢        π        ⁢                                  ⁢                  ED          4                            16        ⁢                                  ⁢                  h          3                      .  In this way, the relationship between the horizontal stiffness K and the vertical bearing capacity N of the cylindrical rubber support is
  K  =                    3        ⁢                                  ⁢        E                    4        ⁢                                  ⁢        f              ×                  D        2                    h        3              ⁢          N      .      E and f are constants, h cannot be too big, D cannot be too small, thus the horizontal stiffness of the rubber earthquake-isolation support cannot be too small, and therefore there is still a large part of the seismic energy transmitted through the rubber earthquake-isolation support to the upper structure.
For the structural earthquake isolation, the smaller the horizontal stiffness and damping of the earthquake-isolation support, the better the earthquake-isolation results will be. However, if the horizontal stiffness of the earthquake-isolation support is zero, the earthquake-isolation support will not have a restoring force after the earthquake, and the upper structure will not be restored to the original state; therefore, the earthquake-isolation support still needs a certain level of stiffness.
Thus, an ideal earthquake-isolation support has larger vertical bearing capacity, controllable horizontal stiffness, sufficient bearing capacity of resistance to lateral displacement, and smaller damping.